This invention generally relates to a switching circuit and more particularly to a circuit used as a switch gear circuit in electric vehicles for controlling capacitive loads.
Electric vehicles typically include switch gear circuits designed to control power supply and usage of capacitive loads. In most arrangements a precharge circuit pathway is provided for charging a capacitive load by selectively coupling it with a power source. After the capacitive load is charged sufficiently, a main circuit pathway, which is in parallel with the precharge pathway, connects the power source to the load. After a preselected amount of time, the precharge circuit pathway is opened while the main pathway remains closed.
In typical situations it becomes necessary to disconnect the capacitive load from the power source. Therefore, a relay that can consistently break large currents at high voltages has been included in the main pathway. While such an arrangement has. proven usable, those skilled in the art are always striving to make improvements. One improvement that could be made is to use less-expensive components, which would make the overall system more economical.
This invention provides a circuit arrangement that eliminates the need for a relatively expensive high-voltage relay switch in the main circuit pathway. This invention replaces the relatively expensive component with a very low cost arrangement that is reliable and economical.